I. Field of the Invention
The present invention relates to machine parts with a wear-resistant surface brought into contact with an elongated fibrous member such as a strand or yarn and, more particularly, to textile machine parts.
II. Description of the Prior Art
Many parts brought into contact with a running strand or yarn are included in fiber machines such as spinning machines, weaving machines (looms), knitting machines, braiding machines, and sewing machines. As a result of stronger, harder thread or yarn, the wear-resistant properties of parts brought into contact therewith have become more important. To describe the wear-resistant properties of machine parts in this specification, a weaving machine will be used.
The weaving machine (loom) is a machine for weaving a fabric by crossing warps and a weft. A typical example of a conventional weaving machine is illustrated in FIG. 1. In the weaving machine of FIG. 1, heald 1 and reed 2 are arranged along the moving direction of warps a.
A plurality of healds 1 are arranged corresponding to each of a plurality of warps a to be aligned along the running direction thereof. Each heald 1 has a shape and structure as shown in FIG. 3. Heald 1 has mail 11 at its center and mounting holes 12 at its ends. A warp passes through mail 11 and heald bars (not shown) pass through holes 12 to hold heald 1 to a heald frame. Therefore, parallel healds 1 are mounted in the heald frame through the heald bars passing through holes 12 of healds 1. The frame is vertically moved by a mechanism (not shown), and the heald bars and healds 1 are moved together, thereby vertically moving warps a.
As shown in FIGS. 4 and 5, reed 2 is arranged such that a large number (e.g., 3,000) of reed wires 3 are aligned like a comb at a predetermined pitch and are fixed to rectangular frame 21. Warps a are respectively inserted between adjacent wires 3. As shown in FIG. 2, reed 2 is pivoted in the direction of the arrows to hit and force weft b in the moving direction of warps a to evenly space the yarns.
Referring to FIGS. 1 and 2, many warps a supplied from a thread or yarn supply mechanism (not shown) are moved in the direction shown by the arrows and taken up by take-up mechanism 5. At an intermediate position, warps a pass through mails 11 of healds 1 and between adjacent reed wires 3 of reed 2. Warps a are vertically moved upon vertical movement of healds 1. As shown in FIG. 2, when warps a are alternately located at upper and lower positions, weft b supplied from main nozzle or weft inserting mechanism 4 passes between the upper warps a1 and lower warps a2, and reed 2 is pivoted in the running direction of warps a to beat up weft b. By repeating the above operation, fabric c is woven.
In a conventional fluid jet type weaving machine, weft b is carried by a fluid jet sprayed from main nozzle 4 arranged at the side of the machine. In this case, the pressure of the fluid jet decreases as it is separated from nozzle 4, and thus its carrying force is decreased. A plurality of sub nozzles 31 are arranged at a predetermined pitch along the feed direction of weft b, as shown in FIGS. 6 and 7. A pressurized lfuid is sprayed from nozzles 31 toward weft b from below, so that weft b is supported by the pressurized fluid. As a result, the feed force of the fluid jet can be reinforced.
The heald, reed, and sub nozzles as weaving machine parts described above are normally made of an iron series metal such as carbon steel or stainless steel, which causes the following problems.
When healds 1 are vertically moved together with the frame, there is fuiction between the metal heald bars and holes 12 formed at both ends of each heald 1, and at the same time, friction occurs between warp a and the corresponding inner edge of mail 11. Holes 12 are thus worn by friction with the heald bars and finally become highly damaged. In the worst case, heald 1 becomes detached from the heald bar. The inner edge of mail 11 of heald 1 is also damaged by friction with warp a passing therethrough. Warp a frays because of this damage, and degrades the cloth feeling. In the conventional water jet type weaving machine, droplets of water from a water jet (natural water) used for feeding weft b adhere to the surface of heald 1. Foreign material contained in the water jet reacts with the metal of the heald, and a layer of foreign material is formed on the surface of the heald. Warp a passing through heald 1 frays because of this foreign material layer. At the same time, the thickness of heald 1 is increased due to the presence of the foreign material layer, and adjacent healds 1 are brought into contact with each other, thus interfering with heald movement.
In order to solve the above problem, the following solution has been attempted in recent years. A surface layer of a material different from that of the heald is formed on the surface of the heald to prevent it from being worn by friction between the heald and the heald bar and between the warp and the heald, and to prevent formation of a foreign material layer on the heald surface.
The surface layer formed on the heald surface must satisfy the following requirements. The surface layer must have wear-resistant properties able to prevent wear of the heald in association with friction with the heald bar and the warp. At the same time, the suface layer must be thin and firmly formed on the heald surface. Upon formation of such a surface layer, the properties of heald itself must not be degraded and surface finishing, such as polishing, should not be required. The latter requirement is based on the assumption that, since the heald is small, surface finishing is cumbersome.
The same solution as described above has also been attempted for the reed. A surface layer of a material different from that of the reed is formed on the reed wire surface to reduce friction with the warp.
This surface layer must satisfy the following requirements. The surface layer must have enough wear-resistance to endure friction with the warp. Since the reed wire is elastically flexed to follow the movement of the warp, the surface layer must be firmly formed on the reed wire surface so as not to peel therefrom. Furthermore, the surface layer must be thin, since the distance between adjacent reed wires is very small.
The sub nozzle used in the fluid jet type weaving machine presents the following problem. As shown in FIGS. 6 and 7, nozzle 31 is fixed at a predetermined position and is located under warps a when they are horizontally aligned. When warps a are separated, nozzle 31 is located between warps a, as shown in FIGS. 6 and 7 and sprays the pressurized fluid on weft b. In this case, when nozzle 31 is moved relative to the pair of warps a and catches them, warps a fray, thus degrading the cloth feeling. Therefore, nozzle 31 must have a smooth outer surface to allow sliding of warps a when nozzle 31 is brought into contact with warps a. Furthermore, the outer surface of nozzle 31 is worn due to contact with warps a and must have good wear-resistant property.
The same solution as for the healds and reed wires has also been attempted for the sub nozzle. A surface layer of a material different from that of the sub nozzle is formed thereon, to prevent the outer surface of the sub nozzle from snagging the warps and from being worn by friction with the warps.
The surface layer formed on the nozzle surface must satisfy the following requirements. The surface layer must have a sliding property for allowing smooth sliding of the warps upon contact therewith. The surface layer must also have enough wear-resistance to endure friction with the warps. The surface layer must be firmly formed on the nozzle surface and must not degrade the nozzle material. After formation of such a surface layer, surface finishing such as polishing should not be required.
In addition to the healds, reed wires, and sub nozzles, the conventional weaving machine has other machine parts that are brought into sliding contact with the warps and the weft. Examples of these parts are a tension roller, a measuring roller, a yarn hook and a needle. For example, the tension roller causes two disks to clamp a yarn therebetween to apply an optimal tension force to the yarn. The measuring roller holds weft according to the width of the fabric. The yarn hook holds the yarn. The needle is a needle member for knitting the yarn. These machine parts are normally made of an iron series material.
The use of these machine parts has the following problems. Since the parts are operated while being in sliding contact with the warp or weft, when sliding contact is poor, the yarn frays to degrade feeling of the resultant cloth. Therefore, the parts must have smooth surfaces to prevent the yarn from being snagged thereby during operation. Furthermore, since the surfaces of the machine parts are worn due to sliding contact with the yarn, these surfaces must have a good wear-resistant property.
In order to prevent the yarn from fraying and the cloth feeling from being degraded, surface layers of a material different from that of the machine parts must be formed thereon.
These surface layers must satisfy the following requirements. Each surface layer must be smooth or have a sliding property good enough to allow smooth sliding contact with the running yarn, and have a good wear-resistant property. The surface layer must also be firmly formed on the parts surface and must not degrade the material of the machine parts. The surface layer should not require surface finishing after its formation. Furthermore, the surface layer must be formable on even small, complicated machine parts.
Methods of forming a surface layer on a heald, a reed wire, a sub nozzle or other machine parts are exemplified by (a) a hard chromium plating method, (b) a PVD (physical vapor deposition) method, (c) a flame spraying method, or (d) a CVD (chemical vapor deposition) method. However, each method presents the following problems and cannot be used in practical applications. Formation of a surface layer on a surface of a reed wire is exemplified below.
(a) A film formed by the hard chromium plating method has a good wear-resistant property, but poor resistance to chemicals. Since an oil is applied to the surface of warps to improve its binding force, the surface layer on the reed wire often reacts chemically with the oil.
(b) Vapor evaporation is a typical example of the PVD method. If titanium carbide is evaporated and formed on the surface of the reed wire, it has poor adhesion with the reed wire and tends to peel off when the reed wire elastically flexes. In the evaporation step, a film tends not to be formed on an unexposed poriton to the evaporation source, and thus, a uniform film cannot be formed.
(c) If a tungsten carbide film is formed by flame spraying on the surface of the reed wire, the film surface must be polished. The film formed by flame spraying is very hard, and the reed wire is very thin. It is thus difficult to perform such polishing.
(d) If a titanium carbide film is formed by the CVD method on the surface of the reed wire, a high temperature of 700 to 1,200.degree. C. is required. Elasticity of the reed wire is degraded at such high temperatures.
When the films are formed on the surfaces of healds, sub nozzles and other machine parts according to methods (a) to (d), the resultant films cannot satisfy the specific requirements and thus cannot be used in practice.